Now, let's do a summary.
The first thing is that we saw that the definition of Risk
and the use of Farmer’s Diagram
allow us to define different operational areas.
We started using three different categories, they were:
Normal operations, transients and accidents.
Also, we saw that the fundamental elements
of safety analysis are the models that simulate the response of the plant,
receiving three different inputs:
the event itself, the operator or equipment failures
and the initial conditions.
Based on this, it was possible to improve safety.
Later, we saw that the Defense-in-Depth was defined in 10CFR50,
based on three different levels of safety.
Level one states that the redundancy is a must to improve safety.
The second level states that there is no perfect system,
and that Defense-in-Depth must avoid or limit damage when an accident happen.
And third level, states or means or says that there would be
additional safety systems for unlikely accidents,
and that they have to be diverse.
And by diverse we mean that the result must be the same,
but the strategies to achieve the goal must be different.
Also, the Defense-in-Depth can be divided
in different categories. They are:
Seismic category, electrical and mechanical.
And finally, we'll have the quality list.
And...
...also, we have technical specifications.
The Technical Specifications are a set of requirements for different items,
needed to preserve our deterministic analysis.
They included Operability, Safety Limits,
LCO's, or Limiting Conditions for Operation,
Actions and Surveillance Requirements.
Finally, we have the probabilistic analysis
that was an improvement over the deterministic analysis.
And there, we define an extra area for high unlikely events to happen
that were the severe accidents.
And with all this, we can say that we have finished this third Unit.